Electrical apparatus



Jan. 7, 1936. H. M. DRESSEL ELECTRICAL APPARATUS Filed June 16, 1954 ONHNHHN FIG.4.

INVENTOR HENRY MDRESS EL BY W ATTORNEY with a transformer.

Patented Jan. 7, 1936 P T N ELECTRICAL APPARATUS Henry M. Dressell, Chicago, llll., assignor to @ah Ma-nutacturing Company, Chicago, llll.

Application June 16, 1934, Serial N01 recess Claims.

This invention relates to an electrical apparatus and particularly to vibrators. In connection with the use of radios on automobiles, aeroplanes and the like, it is desirable to energize the entire system from a single source such as a storage battery. I

In order to obtain the required plate poten-- tials, recourse is had to a buzzer in association The interrupted low voltage currents are impressed upon the transformer and then rectified and filtered. Difiiculty has been experienced in obtaining a buzzer which is symmetrical both electrically and mechanically and which will operate in a satisfactory manner. As a rule, buzzers have a vibrating reed which operates between a pair of spaced contacts. In the normal position of rest, either the reed is eccentric with respect to the magnetic field or one ofthe contacts is closed.

One of these expedients has heretofore been necessary to make the buzzer self-starting. Both of these expedients have a deleterious effect upon the wave shape of the interrupted currents and tend to distort one half of a cycle with respect to the other half of the cycle thus making filtration of the rectifier currents diffl cult.

An object of this invention is to devise a simple vibrator which is free of the above objections and has a symmetrical output.

Referring to the drawing, Figure 1 is an elevation view of a device embodying this invention.

Figure 2 is a side view.

Figure 3 is a section on line 3--3 of Figure 1.

Figure 4 is a schematic diagram of the buzzer circuit.

The buzzer comprises a pair of elongated supporting members i and 2, preferably, though not necessarily, of some metal. Both of these members have bends 3 on them, terminating in pole construction 5. These pole constructions are of magnetic material such as iron and may or may not be integral with i and 2. The pole construction comprises a supporting member 6 forming a part of a main body portion, the latter having a pair of wings 8. The wings may be of any shape and preferably terminate in edges 9, between which opposing edges there is an air gap. Member 6 supports a magnetizing coil i2. Disposed above each member i3 is a quantity of mica it, the portion thereof between coils i 2 being flared out at l5. Coils i2 are of the usual" spool construction and are rigidly maintained by mica bridge it. A pair of bolts it, rigidly fastens the mica to the extreme tips ll of member 6. J

The bottom free ends of elongated members I! and 2 are maintained in spaced relationship by a pair of insulating blocks 20 and 2!. The entire 5 assembly is suitably perforated to permit a pair of bolts 22 to pass therethrough. In order to prevent bolts 22 from completing a circuit between members l and 2, insulating sleeves 23 are provided around the bolts. Suitable nuts maintain the assembly intact. Elongated members i and 2 each carry near bent portion 3 a stationary contact 3B and 3!. These contacts may be suitably adjusted by nuts 32, cooperating with threaded portions thereof. 15

Supported between members i and 2, is a reed 35. Reed 35 carries an armature 36 extending between the opposing pole faces i of the pole structure and is short enough so that it may vibrate transversally of the air gap without en- 2 gaging any of the pole pieces. The bottom of reed 35 carries a movable contact structure comprising a pair of bracing members 40 and it extended upwardly alongside of reed 35. On the outside of members 30 and M are a pair of small spaced blocks 62 and 63. On the outside of these spaced blocks are spring members 45 and 06 bearing at their free ends contacts l? and 48. On the outside of spring members 45 and it are a pair of rigid members 50 and 58 having suitable apertures 52 through which movable contacts 3-? and 18 may telescope. The entire assembly is rigidly maintained by rivets 55. The entire reed assembly is supported on a strip 55 of spring steel. Strip 56 has one end thereof rigidly joined to the reed assembly preferably at the center thereof as shown in the drawing. The lower end of spring 56 is rigidly clamped between insulating blocks 20 and 2t.

Reed 35 is of a gauge customary in the art and for automobile radio purposes generally comprises a strip of tempered spring steel about 1%" long and wide and of about .014 thick. The bracing members E-ii, ll, 32, and 63 are preferably of metal and are thick enough so that they have substantially no tendency to yield in the normal operation of the device.

Springs :35 and bearing movable contact members may be of the same Width and thickness as reed S5 and may be about half as long. Flexible spring 55, however, is substantially thinner than any of the other spring members and in this instance, may have a thickness of about .004" with an efi'ective free length of about f and the same width as the remaining elements of the reed structure. These dimensions are merely exemplary. Flexible spring 56 is sufliciently weak so that when the buzzer is idle the entire reed structure will tend to sag on spring 56 depending on how the buzzer is positioned.

The entire buzzer is supported by means of a rigid member 60 clamped adjacent spring 56 and between insulators 20 and 2!. The bottom portion of member 60 has a pair of apertures into which grommets 6! of rubber are disposed. A supporting member 62 has its upper end 63 suitably apertured and the entire assembly is maintained by means of a pair of rivets 6d. Because of the grommets 6i operated members 60 and 62, it is clear that a resilient support for the entire structure is provided.

Referring to Figure 4, a transformer 65 having secondary 66 is provided with a single primary B1. The center 68 of primary 6? may be connected through a suitable switch 69 to one terminal of the battery ill. The other terminal of battery ill is connected to reed 35 and coils l2. The free terminals of coils l2 are connected by wires H and F2 to the outer ends of primary 6?. Stationary contacts 30 and 3! are connected .to wires 12 and H respectively.

Assuming that switch 69 is closed and an initial impulse to reed 35 is given, either by accidental vibration or because of the position of the device, it is clear that reed 35 will begin to vibrate.

What is claimed is:

, 1. A buzzer comprising a magnetic field structure including a pair of opposed pole faces sep-' arated by an air gap, a pair of magnetizing coils for said field structure, one coil on each side of said air gap, a vertically disposed magnetizable reed adapted to vibrate in said air gap and to.

complete a magnetic circuit with one pole face, a pair of stationary contacts disposed on each side of said reed, a pair of movable contacts carried by said reed cooperating with said stationary contacts, circuit connections whereby each cooperating pair of contacts controls a magnetizing coil for attracting the reed toward a pole face,

said contacts and pole pieces being symmetrical with respect to said reed with said contacts open in vertical position of said reed, and means for supporting said reed at one end thereof, said means including a resilient element having enough stiffness to support said reed vertically but having substantially no stiffness for impelling said reed along a horizontal axis whereby said reed tends to rest in one of its two extreme positions.

2. A buzzer comprising a pair of vertical magnetizable members, each having one end thereof formed as a pole piece, said two pole pieces being disposed opposite each other and separated by an air gap, means for rigidly supporting said members in predetermined relationship, a magnetizing coil for each member, a stationary con tact carried by each member, a flexible magnetizable reed disposed between said two members and supported at one end thereof only, the free end of said reed being adapted to vibrate in said air gap, movable contacts carried by said reed and adapted to cooperate with said stationary contacts, circuit connections whereby each magnetizing coil is controlled by one pair of said contacts, said contacts and pole pieces being symmetrical with respect to said reed with said contacts open in vertical position of said reed, andmeans comprising a thin flexible metallic spring for supporting said reed at one end thereof, said spring 26 being just strong enough to maintain the reed in position but being so weak as to impress substantially no bias on the reed whereby said reed tends to rest in one of its two extreme positions.

3. The structure of claim 2 herein said entire buzzer is resiliently supported in rubber.

4. The structure of claim 2 herein said movable contacts on said reed are supported by spring members whereby said reed tends to rest in one of its two extreme positions.

5. A buzzer comprising a pair of vertically disposed magnetizable members, one end of each of said members being formed as a pole piece, means for maintaining the other ends of said members in rigid relationship for defining an air gap between said pole pieces, a magnetizing coil mounted on each of said members adjacent a pole piece, a bridge of non-magnetic material rigidly uniting the pole pieces of said members for maintaining said magnetizing structure intact, a pair of stationary contacts carried by said members each member carrying one contact, a flexible magnetic reed disposed between said members and having one end disposed in said air gap and adapted to vibrate therein and being supported at 4,5

its other end, a pair of movable contacts carried by said reed and cooperating with said stationary.- contacts, said contacts and pole pieces being symmetrical with respect to the reed with said contacts open in vertical position of said reed, circuit connections whereby each pair of'cooperating contact controls a magnetizing coil, and means for supporting said reed so that substantially no spring bias is imposed thereon.

a HENRY M. DRESSEL. 

